Apparatus for use in intercepting leakage of fumes and dust from electricarc furnaces



Jan. 5, 1965 ROKURO YAGI 3,164,653

APPARATUS FOR USE IN INTERCEPTING LEAKAGE OF FUMES AND DUST FROM ELECTRIC-ARC FURNACES 2 Sheets-Sheet 1 Filed Aug. 20, 1962 1;; ref; for.

40/: ur a yay/ r w Afforneys ROKURO YAGI APPARATUS FOR USE IN INTERCEPTING LEAKAGE OF FUMES Jan. 5, 1965 3,164,658

AND DUST FROM ELECTRIC-ARC FURNACES 2 Sheets-Sheet 2 Filed Aug. 20, 1962 United States Patent Ofitice 3,164,658 Patented Jan. 5, 1965 APPARATUS FOR USE IN INTERCEPTING LEAK- AGE OF FUMES AND DUST FROM ELECTRIC- ARC FURNACES Rokuro Yagi, 48 Hakusan, Narumi-cho, Aichi-gun,

Aichi-ken, Japan Filed Aug. 20, 1962, Ser. No. 217,941 1 Claim. (Cl. 13-9) This invention relates to an apparatus for use in intercepting leakage of fumes and dust from electric-arc furnaces. More particularly, this invention relates to an apparatus for use in preventing smoke or gases or vapor or dust from escaping through a clearance or gap between the periphery of electrodes and the border of roof openings provided for inserting the electrodes of an electric-arc furnace in which a metal such as steel or pig iron is being subjected to refining or smelting, characterized in arranging a perforated annular pipe encircling the periphery of individual electrodes and supplying to said annular pipe a compressed gas which is allowed to gush out in a jet into the furnace from apertures provided in the inner side of the annular pipe so as to introduce the fumes and dust into a dust-collecting pipe while preventing the leakage of fumes and dust out of the furnace through said gap into the environment.

In order that the invention may be better understood reference will now be made to the accompanying drawings, in which:

FIGURE 1 is a section through a conventional apparatus for preventing the fumes and dust from escaping from an electric-arc furnace;

FIGURE 2 is a section through portion A in FIG- URE 1;

FIGURE 3 is a side elevation of an apparatus according to the invention;

FIGURE 4 is a section through portion B in FIG- URE 3;

FIGURE 5 is a plan of an annular pipe arranged in an apparatus according to the invention; and

FIGURE 6 is a section of the pipe in FIGURE 5.

The conventional apparatus of this kind comprises as shown in FIGURES 1 and 2 hood 9 for covering cinder notch 6 and hood 10 for covering furnace roof 2, hood 9 and hood 10 being communicated with one another for collecting and introducing into dust-collecting pipe 8 the fumes and dust escaping from within an electric-arc furnace through cinder notch 6, cinder notch door 7, and along the periphery of electrodes 5, Le, through a clearance or gap between the periphery of electrodes and roof openings and between the periphery of electrodes and e1ectrode-cooling devices 3 encircling the individual electrodes.

In the prior art it has been observed that the circulation of fumes and dust of high temperatures within the hood, which covers the furnace roof, results in diminished life of roof linings and severe waste of the hood and that a considerable volume of the fumes and dust inevitably leaks through gap 12 between the hood apertures serving for inserting electrodes and the border of the electrodes. Accordingly, a very imperfect satisfaction has been derived heretofore by means of a conventional apparatus for collecting the fumes and dust. For this reason, the leakage of fumes and dust from an electric-arc furnace has been a vital question for the health of workmen and the efficiency of the furnace operation.

To solve this problem the invention provides an apparatus as shown in FIGURES 3 through 6 which comprises annular pipes 13 each of which is mounted on electrodecooling device 3 so as to encircle the corresponding electrode and which is provided in inner side thereof with apertures 4 substantially equally spaced from one another. According to the invention a compressed gas such as air or any suitable kind of such reducing gas as carbon monoxide or such inert gas as nitrogen gas is supplied to the annular pipe in order to cause the major portion of the introduced gas to gush out in a jet into the furnace, a minute portion of the gas being allowed to vanish into the air surrounding the furnace, so that the leakage of fumes and dust from the furnace through gap 14 be tween electrodes 5 and roof openings and between electrodes 5 and electrode-cooling devices 3 is intercepted while introducing the fumes and dust entirely into dustcollecting pipe 9 through cinder notch 6 and cinder notch door 7.

Advantages attending upon the practice of the invention over the prior art involve no leakage of fumes and dust out of the furnace and omission of the furnace hood which results in preservation of the lining bricks of furnace roof, facilitating the investigation of the same and preventing the heat generation in the roof bricks adjacent to roof openings which in the prior art has occurred by leakage of fumes and dust into the furnace hood. Accordingly, the apparatus according to the invention affords a longer life of bricks, easiness of furnace operation, and a considerable reduction in man-power. In addition, a compressed gas comprising inert gas or reducing gas blown out into the furnace renders the inside of the furnace positively pressured so that any amount of air outside the furnace is prevented from entering into the furnace while maintaining the inside of the furnace with atmosphere that is inert or of reducing nature as required.

An preferred embodiment of the invention has been described in detail wherein the example is for the purpose of illustrating the preferred embodiment and not for the purpose of limiting the same. For example, the aperture of the annular pipe from which pressured gas is blown out may be of any form such as, for example, of slit in place of round hole.

What I claim as my invention:

In an electric arc furnace including a roof having electrode receiving openings extending therethrough, electrodes extending through said openings, and electrode cooling means disposed about said electrodes, the improvement comprising:

a dust and fume exhaust system effective to minimize contact of hot combustion gases with said roof to prevent attack of said roof and said electrodes by corrosive fumes and dust generated in said furnace, and to prevent escape of fumes and dust through annular spaces between said electrodes and walls defining said openings in said roof, said system comprising:

a first hood covering said furnace roof,

a second hood in communication therewith,

gas bafile means interposed between said first and said second hoods whereby gas flow therebetween is only through an opening substantially below said roof of said furnace,

a dust and fume collecting pipe surmounting said second hood and a cinder notch and a cinder notch door therebelow,

annular pipes encircling said electrodes exteriorly of said roof and concentric with said openings therethrough and with said annular spaces formed between said electrodes and said roof,

gas propelling means for delivering gas under pressure to said annular pipes,

said pipes having spaced gas flow apertures in a radially References Cited by the Examiner inward Wall thereof to direct gas issuing there- UNITED STATES PATENTS from into and through said annular openings to deliver said gas into said furnace to prevent fumes 951,458 3/10 shawhan and dust from escaping upwardly past said electrodes, 5 1,129,377 2/15 Bron fit 13-47 X to cool said roof and to obviate corrosive attack 2,405,236 8/46 et a1 thereof, to maintain a positive gas pressure in said 3,018,096 1/62 Rydlnger X furnace, and to carry said fumes and said dust through said cinder notch and said cinder notch door RICHARD WOOD Primary Exammer' and into said dust collecting pipe. 10 JOSEPH V. TRUHE, Examiner. 

